End Of Thawing Research Articles

Experimental study on a novel vacuum sublimation-rehydration thawing of frozen potatoes.

To realize a quick thawing of frozen potatoes, the experimental investigation of thawing performance was conducted by using a novel vacuum sublimation-rehydration thawing (VSRT) in this study. Frozen diced potatoes (20mm × 20mm × 20mm) with a total mass of 1.5kg were selected as the thawing object. The center temperature of the frozen diced potato was raised from -18°C to 5°C to assess the beginning and end of thawing. The effects of sublimation time, heating plate temperature, and rehydration temperature on thawing time of frozen potatoes were experimentally studied. The VSRT and vacuum steam thawing (VST) were compared in terms of thawing time, hardness, and specific energy consumption. The results showed that the conditions of sublimation time of 25min, heating plate temperature of 30°C, and rehydration temperature of 100°C could effectively shorten the thawing time of VSRT for thawing frozen potatoes. The thawing time of VSRT was only 49% of that of VST. Compared to the hardness of frozen potatoes thawed by VST, the hardness of frozen potatoes thawed by VSRT was closer to that of blanched (unfrozen) potatoes. The specific energy consumption of VSRT was lower than that of VST. PRACTICAL APPLICATION: The quality of frozen potatoes is directly affected by the thawing method used. A novel vacuum sublimation-rehydration thawing was conducted in this study, which can provide a new idea for a reasonable, effective, and quick thawing method for frozen potatoes.

Soil thawing regulates the spring growth onset in tundra and alpine biomes

Soil temperature remains isothermal at 0 °C and water shifts to a liquid phase during soil thawing. Vegetation may receive this process as a signal and a key to restore physiological activity. We aimed to show the relationship between the timing of soil thawing and the spring growth onset. We estimated the delay between the soil thawing and the spring growth onset in 78 sites of the FLUXNET network. We built a soil thawing map derived from modeling for the northern hemisphere and related it to the greenness onset estimated with satellite imagery. Spring onset estimated with GPP time series occurred shortly after soil surface thawing in tundra (1.1 ± 3.5 days) and alpine grasslands (16.6 ± 5.8 days). The association was weaker for deciduous forests (40.3 ± 4.2 days), especially where soils freeze infrequently. Needleleaved forests tended to start the growing season before the end of thawing (−17.4 ± 3.6 days), although observations from remote sensing (MODIS Land Cover Dynamics) indicated that the onset of greenness started after the thawing period (26.8 ± 3.2 days). This study highlights the role of soil temperature at the spring growth onset at high latitudes. Soil thawing becomes less relevant in temperate forests, where soil is occasionally frozen and other climate factors become more important.

Spray freezing decontamination of tailings water at the Colomac Mine

A field pilot scale experiment was conducted to evaluate the efficiency of spray freezing to remove dissolved chemicals from the tailings lake water at the Colomac Mine, NWT. Cores of the spray ice were then taken to the University of Alberta. The distribution of chemicals in the ice cores were determined, then a 1 m long core sample was thawed in a controlled manner to simulate thawing in the field to examine the concentrations of chemicals in the melt water as the columns thawed. For the pilot scale project approximately 30% of the water pumped was frozen, with the remaining water returned to the tailings pond as runoff. Analysis of the water collected from an ice core melted under controlled laboratory conditions showed dissolved chemical removal of 87–99% (depending on the chemical species) after 39% of the spray ice column had melted. Arsenic concentrations were reduced from approximately 19 μg/L to approximately 5 μg/l. Cyanide had 99.2% removal but still remained at a concentration of approximately 350 μg/L. Approximately 60% of the treated water released at the end of the melt contained only 1–17% of the dissolved species. This melt water at the end of thaw would only require minor further treatment, which may significantly reduce overall treatment costs.

Field Assessment of Changes in Pavement Moduli Caused by Freezing and Thawing

Three secondary highways with flexible pavements were instrumented for 18 months to monitor changes in pavement moduli caused by seasonal meteorological changes. Temperatures, water contents, and water phase changes in the subsurface as well as meteorological conditions were recorded every 2 hours throughout the study. Pavement moduli were regularly determined by conducting surveys with a falling weight deflectometer and by performing backcalculations using the program Modulus. The moduli of the base and subgrade typically increased 12 to 4 times, respectively, when frost penetrated the subsurface. When the base and subgrade began to thaw, the moduli decreased substantially. The base moduli decreased the most, typically being about 35 percent of the prefreezing values by the end of thaw. Smaller decreases occurred in the subgrade. The subgrade moduli were about 65 percent of their prefreezing values by the end of thaw. The moduli continued to decrease until thaw was complete and then gradually recovered back to the original prefreezing values. Complete recovery required approximately 4 months. Similar changes in moduli were observed regardless of site or year.

Microwave Thawing of Peaches A Comparative Study of Various Thawing Processes

AbstractThe purpose of the present paper was to determine the influence of various thawing treatments of microwaves and of the air temperature (air 20° C; air 20° C then 4° C) on the exudation of Clingstone peaches, peeled or not, in relation to the stage of maturity. The amount of exudate, its content of total sugars and the fruit browning to the end of thawing were measured. We have previously shown that thawing by microwave energy promotes both a good retention of the water and of the substances dissolved in the cells and a better preservation of the structure and color of the fruits.